Refrigerating apparatus



April 11, 1950 PRESTON 2,503,595

REFRIGERATING APPARATUS Filed Dec. 1, 1945 Patented Apr. 11, 1950 2.503.595 amrosaa'rmc xrrxmros Charles 0. Preston, Dayton, Ohio, assignor to General Motors Corporation, Dayton, Ohio, a corporation of Delaware Application December 1, 1945, Serial No. 632,190

1 Claim. 1

This invention is related to refrigerating apparatus, but more particularly is directed to heat transfer structures of general application.

The eillcient transfer of heat to or from a gas or other medium having low thermal conductivity is a very difficult problem. Such mediums have such poor conductivity that extensive surfaces of a better conducting material must be exposed in intimate contact with the medium. Such surfaces are expensive and tend to obstruct the flow of the medium.

It is an object of my invention to provide within a container an inexpensive efficient means of transferring heat between the medium and the walls of the container.

It is another object of my invention to use wire in an easily manufactured and assembled form for efliciently transferring heat between a medium and the walls of a tube containing the medium.

It is another object of my invention to use as the heat transfer conductor between the gas and the containing walls a member similar to a wire brush in which a stem of twisted wires hold the transverse wire bristles extending between the walls.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawings, wherein a preferred form of the present invention is clearly shown.

In the drawings:

Fig. 1 is a view partly in section of a double tube-type of gas heat exchanger embodying one form of my invention; and

Fig. 2 is a sectional view taken along the lines 22 of Fig. 1.

Heat exchangers have many uses. One form of heat exchanger for fluids is the double tube-type having concentrically arranged tubes in which normally one fluid flows through the inner tube while a second fluid flows in the opposite direction between the inner and outer tubes. The drawings show one form of such a heat exchanger in which there is provided an inner tube 20 connecting at its upper and lower ends with an inlet tube 22 and an outlet tube 24. The upper and lower ends of the tube 20 are surrounded by the rings 26 and 28 which support the outer tube 30 concentrically with the inner tube 20. An inlet tube 32 extends through an aperture in the outer tube so that it communicates with the space between the inner and outer tubes 20 and 30 at the lower end of the heat exchanger, while at the upper end there is provided an outlet tube 34 extending through an aperture to communicate with 2 the upper portion of the space between the inner and outer tubes 20 and 30.

When such a double tube heat exchanger is used for interchanging heat between high conducting fluids, such as water, no particular effort is required to'distribute the heat transfer throughout the water. However, when a fluid of very low heat conductivity such as a gas is used in at least one of the spaces, a special means must be provided to efficiently carry the heat into and out of intimate contact with a greater portion of the gascarrying spaces of the heat interchanger.

Many forms of conductors have been used. The majority of these are some form of sheet material. According to my invention, however, I use wire bristles 31 for conducting heat into or out of intimate contact with the gas within the inner tube 20. Such wire bristles 31 extend transversely between opposite sides of the inner tube and are preferably uniformly spaced along the tube. Where there is only gravity flow within a tube of about 1" in diameter, there should be about of these bristles distributed through each inch of the tubing. Preferably the bristles 31 are of 0.006" steel wire. Where there is forced circulation providing greater flow, more bristles may be used. The wire bristles are held between a plurality of strands 36 and 38 of twisted wire which extend axially within the inner tube 20 from one end to the other. The twisting of the strands holds the wire bristles 31 tightly between the two wires of the stem. The bristles 31 extend transversely between the inner walls of the inner tube 20 in a uniform helical fashion from one end of the inner tube to the other. Each of the bristles 3'! extends half on one side of the stem and half on the other side. They are just a trifle longer than the inner diameter of the tube so that they are slightly column loaded by being pressed into the inner tube so that their ends make a firm contact with the inner walls of the inner tube. The bristles 31 are uniformly distributed radially as shown in Fig. 2.

Since the structure is so very similar to a wire brush having an axial stem, such a heat transfer member may be purchased at a relatively low cost, because of its close resemblance to the structure of a wire brush. The bristles are firmly held in place by the stem, so that the assembly can be readily inserted within the interior of the inner tube without any difliculty and with a minimum of time and effort. It provides a most excellent arrangement for rapidly transferring heat between the gaseous medium within the inner tube 20 and the walls of this tube.

proves the heat transfer.

screen material should be corrugated to a height which is at least equal to the width of the space between the inner and outer tubes 20 and 30 so that it will press resiliently against the walls thereof. Thus when a gas flows through the inner tube 30 heat will be readily transferred between it and the inner tube 20 which will also transfer heat through the corrugated wire structure 4| to the gaseous or other fluid between the inner and outer tubes 20 and 30.

By this arrangement a very efllcient inexpensive gas heat interchanger is provided which may be used in 'many applications. The bristles 31 provide emcient heat transfer between the gas and the walls of the tube 20 from which the heat transfer can be carried further by any suitable means. The bristles 31 should be uniform in length and concentrically arranged with respect to the axis of the stem composed of the wires 36 and iii so that both ends of every bristle are pressed flrmly in contact with the inner walls -of the tube 20. The twisting of the wire stem arranges the bristles in the form of a double helix causing the gas to tend to flow in a hellcal pattern through the inner tube 20 to improve the heat transfer. The wire bristles are very efllcient in heat transfer and they cause turbulence in the flow of the gas which further im- 4 While the form of of the invention as herein disclosed, constitutes a preferred form.itistobeimderatoodthatotherforms might be adopted, as may come within the scope of the claims which follow.

What is claimed is as follows: Aheattransferstructnreeomprisingatube portion, a wire member within the tube portion, said wire member being formed of a stem of heavy twisted wire members extending axially within the tube portion and fine substantially straight stiff wire bristles extending transversely through the stem and having their ends in flrm contact with opposite wall portions of the tube portion, means for conducting a first fluid through the interior of said tube portion, and means on the outside of said tube portion for bringing a second fluid in heat exchange relation with the tube portion.

' CHARLES C. PRESTON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,094,667 Masten Apr. 28, 1914 1,610,000 Fay Dec. 7, 1926 1,854,619 Mortensen Apr. 19, 1932 2,310,970 Limpert Feb. 16, 1943 2,428,993 Reichelderfer Oct. 14, 1947 FOREIGN PATENTS Number Country Date 425,376 Great Britain Mar. 13, 1935 483,642 Great Britain Apr. 25, 1938 

